Relocation Anxiety..Help!

Please don’t rip me to shreds in the comments, I am genuinely asking for helpful advice since I’ve never had to do this before. I also cross posted in r/dogs trying to get some advice.

I have a 1.5 year old intact male Mastador, definitely a mama’s boy since it’s always just been us, and aside from the very rare occasional accident (typically my fault for missing his cue or he’s feeling unwell) he is fully potty trained. Thrives on the routine we have, knows basic commands and listens very well, but has severe separation anxiety.

Recently I have switched shifts at work and had to create a new routine with him, to which he has done a wonderful job adapting to without any problems. During the switch in shifts at work I also lost my father, and even during that chaos he still was a perfectly good boy. Part of my switch in shifts now also requires me to work longer hours, so I am relocating closer to work to allow more time with him by getting to go home on my breaks and not having a long commute.

I have kept the same routine with him as far as the time line of waking/pottying/exercising/eating/snuggles, and have been sure to give him extra praises and treats for basic things as well as extra exercise and undivided attention. The problem I am facing is at bedtime he nervous paces, pants, and whines and eventually has an accident in the house, no matter how many times I take him outside and get up to comfort him throughout the night. It’s becoming exhausting only sleeping for 45 minutes at a time because he’s so anxious.

I know he is capable of holding it 8-12 hours, but I make sure he gets to go outside minimum every 6 currently, and he still continues to have accidents. He is fully crate trained, but at the old house he was to the point of sleeping in the breezeway with a baby gate closed to the rest of the house, and I’d leave the crate open for him to do as he wished as he doesn’t seem to care much for doggy beds. I followed this same pattern at the new house, but he cannot settle in for the night. I’ve never been successful with letting him sleep in my room as he either marks the bed or thinks it’s playtime, he’s always done best in his own quiet area for rest.

He still has his own original crate, toys, raised dog feeder, radio, and pillows in hopes that his own familiar things would have a calming effect on him, and I’ve tried treating him with some high value treats and new toys. I have taken him to the vet to rule out any medical issues and have an appointment to get him neutered, the vet thinks he’s just a severely anxious dog. The medication he has is only PRN and I don’t want to give it to him routinely as he’s never needed it until now.

I am looking for advice on how to help ease his anxiety and get him used to the new home; I’ve tried everything I can think of, and I feel like I’m failing him by not being able to comfort him correctly during this transition together.